In a natural gas distribution system, resilient pipes, such as polyethylene pipes, are frequently used for the underground distribution of natural gas.
Leaks in natural gas lines must be attended to quickly as natural gas is flammable. Furthermore, as the natural gas in such lines is under pressure, a leak of is natural gas (e.g., as a result of a breach in the line due to third party damages or other reasons) must be attended to quickly to limit the spreading of the natural gas.
U.S. Pat. No. 5,152,497, issued to Bissell on Oct. 6, 1992, and U.S. Pat. No. 5,219,146, issued to Thompson on Jun. 15, 1993, each disclose tools for squeezing resilient pipes in order to reduce the flow of natural gas upstream of the leaks or breaches. These tools are manually actuated, as it would be hazardous to use any electrical source in the vicinity of a natural gas leak. Also, an operator of these tools must be close to the mechanism to operate the tool. However, for safety reasons, the operator is often precluded from entering the excavated hole in which the natural gas leak has occurred. Accordingly, pipe access holes must be excavated upstream and/or downstream of the leak to safely reduce the fluid flow through the pipe. This results in an increase in the time of intervention. It is pointed out, however, that squeezing tools are not limited to being used for emergency leak blocking operations on pipes, whereby an operator may be in the vicinity of a pipe for the squeezing thereof.
Squeezing tools must provide given performances of blocking to the pipes they are squeezing. For instance, the blocking of a pipe to reduce a fluid flow below 300 L/hour is a known safety practice in the industry. In designing squeezing tools apt to perform such blocking of pipes, opposed design factors are taken into account. The tools must be as light as possible to be readily maneuverable. On the other hand, they must often squeeze pipes of relatively large diameter, for instance above four inches, whereby they must be rigid and sturdily built.